Intrusive thoughts, flashbacks, panic attacks and sudden physiologicalarousal are each experienced as involuntary, are difficult to control, andlead to considerable distress. Such observations have led to the suggestionthat anxiety disorders are associated with the operation of automaticinformation-processing biases. Clinical and experimental evidence for thisproposal is reviewed and three different classes of routes to the developmentand modification of these automatic processes are described: an innate route,repetition/habituation, and conscious appraisal. The review focuses inparticular on the third route, proposing that automatic processing biasescan be altered by accessing and modifying conscious appraisals of internaland external events. Indirect evidence is provided by selective attentionparadigms in anxiety, treatment studies and clinical observations, althoughfurther research will be necessary for a direct test of the pathway. Theimplications for the theory and practice of psychological therapy for anxiety disorders are described.